Ultra high frequency switching device



' March 30, 1948f H. J. MCCARTHY ULTRA HIGH FREQUENCY SWITCHING DEVICE Filed May 24, 1944 INVENTOR. HENRY J. 'M' CARTHY Qv L my, ATTORNEY Patented Mar. 30, 1948 TENT. OFFICE ULTRA HIGH FREQUENCY SWITCHING DEVICE I Henry J. McCarthy, Danvers, Mass, assignor to Sylvania Electric Products Inc., Salem, Mass, a corporation of Massachusetts Application May 24, 1944, Serial No. 537,143

This invention relates to radio tubes and similar devices and particularly to tubes for automatic switching from receiving to transmitting on the same antenna, particularly at ultra-high frequencies, and in radio location and direction finding equipment.

Such tubes often employ a copper resonating circuit extendin into a sealed tube filled with a gas comprising water vapor. The latter gradually disappears or cleans up during operation, reducing the life of the tube.

An object and advantage of the invention is to increase the tube life by preventing such clean p A feature of the invention is the use of a protective layer over certain of the copper parts which are subject to reaction with the gases inside the tube. A particular feature is a coating of copper oXide over only the copper surface external to the resonator.

Other features, objects and advantages of the invention will be apparent from the following specification, taken in connection with the accompanying drawing; in which:

Figure 1 is a general external view of the device of my invention; 1

Figure 2 is a schematic circuit diagram of the device; and

Figure 3 is a sectional view of the device.

In the figures, the glass tube I has sealed into it a gas comprising water vapor, and hydrogen at a pressure of a few millimeters. For example, the water vapor may have a pressure of 7 millimeters" of mercury, and the hydrogen 10 mm. The copper discs 2, 3 are sealed through the sides of the glass tube I and copper frustrums 9, It of a cone extend from each disc toward and in register with the other. The keep-alive electrode 1 is sealed through the top of the tube and extends to the space near the gap between the two frustra 9 and Ill which are spaced from each other. The copper discs extend through the glass wall I! of tube I and are connected together by an annular copper ring 4 joining their circumf-erences outside the tube I. The lead-in wires are the axial conductors 5, 6 of a coaxial cable whose outer conductors are hollow copper tubes I8, IS. The axial conductor of each cable is formed into a loop 20, 2| at the open end of the cable where the cable is joined to the interior of the ring 4. The end of the loop is, of course, connected to the ring 4 in the usual manner to provide coupling between the coaxial cable and the resonant circuit of which the ring 4 is a part.

The discs 2, 3 with their cones 9, Ill and ring 4,

Claims. (01. 315-5) form a resonating chamber, or cavity, [2, l3. Cavity I3 is external to the tube I and cavity I2 is inside tube i, but resulting cavity is essentially a single unit electrically. The space between the ends of cones 9, and Ill, forms the resonator gap l I. The input is coupled to the resonator by loop '2 I, and the output coupled by loop 20.

In operation, the tube will pass the input of loop 20 to the output loop 2| and thence to a receiving circuit if the input is of low enough value for that circuit to handle. If, however, the input is too high, for example, an input directly from a transmitter on the same antenna, an electric discharge will occur in the gas in gap I I, destroying the resonance so that the input signal will not reach the receiver. The keep-alive electrode "I is connected to the ring 4 through a battery It and a ballast resistance I5 to insure the presence of sufficient ions for such a discharge to start. A plate It is generally fixed to electrode I just above the disc 2.

The surfaces of the copper discs 2, 3 are clean and free of oxide to prevent losses in the resonating circuit except in the inside of the frustroconical portion 9 of the resonating electrode, where a copper oxide coating 8 is placed. I have found that if the copper oxide is placed in this position it is unnecessary to place it on the surfaces inside the resonating chamber where the losses caused by it would be much greater.

Tubes according to my invention may be made by coating the copper discs 4, 5 with oxide or borate, as in my co-pending application Serial No. 510,225, filed November 13, 1943, now Patent No. 2,423,426, granted July 6, 1947, and sealing them into the glass envelope l as there explained. After sealing, the discs will be covered over their entire exposed surface with red copper oxide. A protective coating of lacquer is placed over the portions such as 4, which are to retain their oxide coating, but not over their remaining surface, and then the tube is dipped into acid to remove the oxide from the remainder of the surface, leaving it bright and shiny, The lacquer is then removed with a proper solvent, leaving the oxide on the desired portions of the discs.

What I claim is:

1. An ultra high frequency switching tube comprising a high-frequency copper resonator, an atmosphere comprising water vapor, a keepalive electrode near a part of said resonator, and a coating of water vapor resistant material only on the part of said resonator in the immediate vicinity of said keep-alive electrode within the tube for preventing clean up of the water vapor.

2. The combination of claim 1, in which the coating is red copper oxide.

3. An ultra high frequency switching tube comprising an envelope enclosing an atmosphere comprising water vapor, a copper disc having its inner edge formed to a frustrum of a cone sealed inside said envelope, at keep-alive electrode extending into said frustrum, and a coating of red copper oxide on only the geometrically inside surface of said frustrum within the tube for preventing clean up of water vapor.

4. An ultra high frequency switching tube comprising an envelope enclosing an atmosphere comprising water vapor, two copper discs having their inside edges in the shape of frustra of cones and placed in register with each other with said frustra extending toward each other but spaced from each other, a keep-alive electrode extending into one of said frustra from the larger base thereof, and a coating of water vapor resistant 20 2,353,743

4 material only on the side of said frustrum facing away from said other frustrum within the tube for preventing clean up of water vapor.

5. The combination of claim 4, in which the coating is red copper oxide.

HENRY J. MCCARTHY.

m file of this patent:

UNITED STATES PATENTS Number Name Date 1,432,867 Kelly Oct. 24, 1922 1,694,190 Ruben Dec. 4, 1928 2,065,947 Nauth Dec. 29, 1936 2,075,855 Kilgore Apr. 6, 1937 2,263,648 Salzberg Nov. 25, 1941 2,304,540 Cassen Dec. 8, 1942 McArthur July 18, 1944 

